First Data on Late Cretaceous Terrigenous Deposits of the Upper Part of the Zhuravlevka–Amur Terrane Section in the Lower Amur River Area: Evidence from U/Pb Detrital Zircon Geochronology

• Published in: Russian journal of Pacific geology 2024, Vol.18 (3), p.263-272
• Main Authors: Alexandrov, I. A., Malinovsky, A. I., Ivin, V. V., Budnitskiy, S. Yu
• Format: Article
• Language: English
• Subjects: Age; Age structure; Cretaceous; Detritus; Distribution patterns; Earth and Environmental Science; Earth Sciences; Fluvial deposits; Geochronometry; Geology; Rivers; Rock; Rocks; Sediment; Sediments; Terrigenous sediments; Zircon
• ISSN: 1819-7140; 1819-7159
• DOI: 10.1134/S1819714024700039

The paper reports data on the age and composition of poorly studied Cretaceous clastic rocks of the Lower Amur River area, which are part of the Zhuravlevka–Amur terrane and are attributed to the Berriasian–Valanginian Komsomolsk series. U/Pb dating of detrital zircons yielded reliable dates of 99 and 90 Ma for the Gorin and Pioneer formations, respectively. Thus, a sedimentary complex with a Late Cretaceous sedimentation age was identified for the first time in the Sikhote-Alin orogenic belt based on detrital zircon geochronology. In composition and detrital zircon age distribution pattern, the studied rocks are more similar to sediments of the upper, Hauterivian–Albian part of the Zhuravlevka–Amur terrane section rather than to those of the lower, Berriasian–Valanginian part. In rocks of the Pioneer Formation, the youngest zircon population with an age of about 90 Ma makes up more than 40% of all dated grains. The main source of detrital material of this age was probably proximal andesites hosting the Mnogovershinnoe deposit and granitoids of the Nizhneamurskii Complex. The source of detritus for sediments of the ∼99 Ma Gorin Formation was probably felsic rocks from the Albian–Cenomanian igneous province of Pacific Asia. The discrepancy between the Late Cretaceous age obtained by us and the paleontologically established Berriasian–Valanginian stratigraphic age of the formations requires additional research. New data on the Late Cretaceous age of the Zhuravlevka–Amur sediments of strike-slip marginal-continental basin requires revision of the geologic evolution of the terrane and the entire Sikhote-Alin orogenic belt.